Conceptual models are an essential part of groundwater investigations. The conceptualization process has lacked formality in the past, and has depended on the development of a set of 2-D cross-sections to portray a 3-D picture of groundwater flow as a means of bringing together the numerous and diverse relevant data sets. A more structured approach to developing the hydrogeological framework for the conceptual model is advocated using a 3-D visualization package to assemble the data, and working in three dimensions from the outset. The new method is tested on the complex central part of the English South Downs Chalk aquifer. Although the data needs areintensive, the model is extremely valuable in realisinga number of facets of groundwater flow previouslyunidentified. Other key advantages are that the 3-D model is flexible and can be amended from time to time without the need to start afresh, and that it provides a data platform and a means of further analysis bothin itself and in hydrogeological software such asMODFLOW.